Update: Ooof. Having QuickTime Player open while doing a RAM preview makes the RAM preview stutter. I quit the player, and now the RAM preview plays back without dropping a frame, says it's 24 FPS, but the RAM preview playback is slow: iE, a tenor sounds like a baritone. Trashing cache, restarting, no luck.
system details in my profile.
ug. I just updated to 7/0/1 DL. Hope that didn't make things worse.